Cooling structure of gas turbine tail pipe

ABSTRACT

A plate spring  6  having a hook-shaped cross section from the lower part is installed in the neighborhood of one end “b” of an impingement-cooling plate  4 . One end “c” on the lower side is fixed to a rib  1   d  by welding, while the other end “b” on the upper side is free, which makes it closely contact with the neighborhood of the other end “b” of the impingement-cooling plate  4  by the elastic force thereof. This state makes it possible to seal a gap formed between the impingement-cooling plate  4  and a transition piece  1  on the side of a rib  1   d , preventing thermal stress generated in the rib  1   d , for example, from affecting the impingement-cooling plate  4.

TECHNICAL FIELD

The present invention relates to a construction that cools the outlet ofa transition piece of a gas turbine by using cooling air.

BACKGROUND ART

Conventionally, gas turbines have transition pieces installed theretofor leading combustion gas of high temperature and high pressuregenerated in a combustor to a turbine portion efficiently. The inletportion of such a transition piece has a configuration so as to beconnected to a combustor basket where combustion gas is generated, whilethe outlet portion thereof is configured so as to be connected to a flowpath of the turbine. The shell portion of a transition piece has awelded construction in which plates having cooling holes are combined.Furthermore, the outlet portion has a rib mounted thereon forreinforcement.

Additionally, a transition piece seal is arranged to each of the insidediameter side and the outside diameter side at the outlet of thetransition piece, thereby restraining leakage of the cooling air from aportion connected to the turbine portion. In this way, by introducingthe cooling air to the outlet portion of the transition piece and bypreventing the cooling air from leaking with the transition piece seal,the outlet of a transition piece is cooled by using the outlet air of acompressor. The construction of a conventional combustor of a gasturbine will be explained again hereinafter by referring to thedrawings.

FIG. 8 is a schematic drawing showing a conventional combustor of a gasturbine. FIG. 9 is a view of a transition piece of the combustor seenfrom the outlet side. In FIG. 8, a combustor 100 of a gas turbineconsists of a combustor basket 110 of a cylindrical shape and atransition piece 120 which is to be engaged into an opening 111 of thecombustor basket 110. The transition piece 120 is comprised of a memberof a cylindrical shape and has the opening 111 of the combustor basket110 inserted and engaged into an inlet portion 121 thereof.

The transition piece 120 has a cross-sectional area thereof graduallynarrowed from the inlet portion 121 thereof, and as shown in FIG. 9, theoutlet portion 122 thereof is shaped in a rectangle that is curved to beshaped into a sector. An illustration is omitted to indicate theabove-mentioned welded construction of a shell portion of the transitionpiece 120 in which plates having cooling holes are combined. Thetransition piece 120 has the outlet portion 122 thereof equipped with aseal-support portion 123 of a circular shape and which has a concavecross section on its periphery. The seal-support portion 123 is engagedwith the outlet portion 122 of the transition piece 120 and fixed bywelding.

Now, back to FIG. 8, the combustor 100 of the gas turbine has the outletportion 122 of the transition piece 120 connected to a combustionpassageway 210 of a turbine 200. The inlet of the combustion passageway210 is formed by an inner shroud 230 and an outer shroud 240 whichsupport Turbine Row 1 stationary blades 220 on both ends. The transitionpiece 120 has the outlet portion 122 thereof located at the inlet of thecombustion passageway 210 and fixed to a casing (not illustrated). A gapbetween the outlet portion 122 of the transition piece 120 and thecombustion passageway 210 of the turbine 200 is sealed by a circularsealing member 125 that has a y-shaped cross-sectional configuration.

The sealing member 125 has a hook-shaped tip 126 thereof inserted into aconcave portion of the seal-support portion 123 which is provided to theoutlet 122 of the transition piece 120 and has a forked-into-two portion127 thereof engaged with the shrouds 230 and 240 of Turbine Row 1stationary blades 220. In a combustor 100 of this gas turbine, pre-mixedair generated in the combustor basket 110 and ignited is ejected into acombustion room 128 of the transition piece 120 and burns, becoming ahigh temperature combustion gas. The combustion gas proceeds through theinside of the transition piece 120 and is then blown into the combustionpassageway 210 of the turbine 200 from the outlet portion 122 thereof asshown with arrow marks C.

As an embodiment of a cooling construction of the above-mentionedtransition piece is disclosed a cooling panel of a gas turbine. (Forexample, see Japanese Patent Application Published 2002-511126.) Also, acombustor of a gas turbine is disclosed. (See Japanese PatentApplication Laid Open 2003-65071, for example.)

However, the above-mentioned conventional cooling construction of atransition piece has a non-uniform cooling effect at the outlet portionof a transition piece, and there is a potentiality of deformation causedby having this portion exposed to combustion gas and heated.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a coolingconstruction of a transition piece of a gas turbine which can enhance acooling effect at the outlet portion of the transition piece even thoughit is constructed in a simple manner.

In order to achieve the above-mentioned object, according to the presentinvention, a gas turbine has two protrusions mounted in a verticaldirection to the main stream in the transition piece, outside of theinside diameter of the gas turbine and in the neighborhood of the outletportion of the transition piece. A multiple-holed plate is mountedbetween the protrusions by fixing it to one protrusion only.

Additionally, in the neighborhood of the outlet portion of thetransition piece and outside of the inside diameter of a gas turbine ismounted an impingement cooling plate which is fixed on only one side ina cantilever state. A gap is sealed by way of an elastic plate mountedbetween one end of the impingement cooling plate which is not fixed andthe transition piece.

Furthermore, a surface confronting the impingement cooling plate of thetransition piece has a plurality of cooling holes made thereinhorizontally, viewed in the direction of combustion gas flow. Thecooling holes are arranged in a plurality of rows in the central portionof the transition piece only.

Moreover, each of a plurality of the transition pieces is provided witha respective transition piece seal and has a protrusion mounted on eachend of the transition piece seals confronting each other, in a mannerthat the protrusions will overlap each other.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic longitudinal cross-sectional view of a coolingconstruction of a transition piece of a gas turbine in accordance withan embodiment of the present invention.

FIG. 2 is a plane view of an impingement cooling plate in accordancewith the embodiment of the present invention.

FIG. 3 is a cross-sectional view of a transition piece 1, includingcooling holes 1 e, viewed in the direction of the combustion gas flow.

FIG. 4 is a cross-sectional view of a transition piece 1, includingcooling holes 1 f, viewed from the direction of combustion gas flow.

FIG. 5 depicts a bottom surface of a transition piece 1.

FIG. 6A and FIG. 6B are transverse sectional views depicting aconstruction of the neighborhood of the ends of the impingement coolingplate.

FIG. 7 depicts the construction of transition piece seals in accordancewith the embodiment of the present invention.

FIG. 8 is a schematic view showing a conventional combustor of a gasturbine.

FIG. 9 is a view of a conventional transition piece of a combustorviewed from the outlet side.

BEST MODE FOR CARRYING OUT OF THE INVENTION

Referring now to the drawings, an embodiment of the present inventionwill be described hereinafter. However, the present invention will notbe limited to the following embodiments. FIG. 1 is a schematiclongitudinal sectional view of a cooling construction of a transitionpiece of a gas turbine in accordance with an embodiment of the presentinvention. This figure shows the state in the neighborhood of the bottompart of an outlet portion of a transition piece. In this figure, 1 is atransition piece, 2 is a transition piece seal and 3 is a Row 1 vaneshroud. On the bottom surface of an outlet portion of the transitionpiece 1, brim-shaped ribs 1 a and 1 b extend downward (toward the insidediameter of a gas turbine), having a slot portion 1 c formedthere-between.

Additionally, the transition piece seal 2, whose cross section is shapedapproximately in a hook, has a rib 2 a, rising in a shape of a brim onone end thereof, which is engaged with the above-mentioned slot portion1 c. On the other hand, the other end of the transition piece seal 2 hasa slot portion 2 b formed thereon, with which is engaged a rib 3 a thatextends from Row 1 vane shroud 3 on a turbine side to the transitionpiece side. As constructed above, the transition piece 1 and Row 1 vaneshroud 3 are connected and sealed by the transition piece seal 2. Here,a portion 3 b which extends upward (toward the outside diameter side ofa gas turbine) from Row 1 vane shroud 3 depicts a stationary vane.

Furthermore, on the bottom surface of the transition piece 1 (namely,outside of the inside diameter side of the gas turbine), a brim-shapedrib 1 d extends downward on the combustion gas upstream side of the rib1 b. Then, an impingement-cooling plate 4 whose cross section isapproximately L-shaped and has a multiple number of holes therein ismounted horizontally, viewed in the direction of the combustion gasflow, between the ribs 1 b and 1 d. One end “a” on the narrow side ofthe cross section thereof is fixed to the rib 1 b by welding, while theother end “b” on the wider side of the cross section covering the ribs 1b and 1 d horizontally is a free end. In other words, theimpingement-cooling plate 4 is fixed only on one end in a cantileverstate. Additionally, the wider-side portion of the impingement-coolingplate 4 has impingement holes 4 c made therein in two rowslongitudinally (vertically to the paper).

In addition, in a neighborhood of the other end “b” of theimpingement-cooling plate 4 stands a pin 5 in a space made with thebottom surface of the transition piece 1, which forms a pre-determinedgap between the impingement-cooling plate 4 and the transition piece 1.On the other hand, in the neighborhood of the other end “b” of theimpingement-cooling plate 4 is mounted a plate spring 6 whose crosssection is shaped in a hook from the lower part. This makes it possiblethat one end “c” of the lower side is fixed to the rib 1 d by welding,while the other end “d” on the upper side is free end, thereby gettingin close contact with the neighborhood of the other end “b” of theimpingement-cooling plate 4 by elastic force thereof. This ensuressealing of the above-mentioned gap which is formed between theimpingement-cooling plate 4 and the transition piece 1 on the side ofthe rib 1 d, for example, preventing thermal stress generated in the rib1 d from affecting the impingement-cooling plate 4.

Furthermore, although not illustrated, the impingement-cooling plate 4may be constructed so as to be fixed to any one of the ribs only betweenthe ribs 1 b and 1 d that are protruding from the bottom surface of thetransition piece 1, without using the pin 5 and the plate spring 6.Concretely, for example, the impingement-cooling plate 4 may have oneend “a” fixed to the rib 1 b by welding and have the other end “b” be afree end, and thereby may have the other end “b” get in close contactwith the rib 1 d by elastic force thereof. This makes it possible toseal the above-mentioned gap formed between the impingement-coolingplate 4 and the transition piece 1 on the side of the rib 1 d, avoidingthermal stress caused to the rib 1 d from affecting theimpingement-cooling plate 4, for example, thereby enabling a decrease inthe number of components and reducing the number of man hours formanufacturing.

Moreover, on the bottom surface of the transition piece 1, cooling holes1 e and 1 f are made therein between the ribs 1 b and 1 d (namely on aface confronting the impingement-cooling plate 4) sequentially from thecombustion gas upstream side, forming a predetermined angle α with thebottom surface of the transition piece 1 toward the combustion gasdownstream side. This is for intensively cooling a portion which reachesa high temperature by arranging cooling holes in two rows in the centralportion at the outlet of the transition piece 1 only, while arrangingthem in one row in the surrounding neighborhood. This will be describedin detail later. As shown with arrow marks A in the figure, compressedair from a compressor (not illustrated herein) once enters a gap betweenthe impingement-cooling plate 4 and the transition piece 1 through theimpingement holes 4 c; flows into the inside of the transition piece 1through the cooling holes 1 e and 1 f; and then, as shown with arrowmarks B, flows along the inner wall surface of the transition piece 1,thus performing film-cooling.

The impingement-cooling plate 4 contributes to enhancement ofimpingement-cooling effect by having impingement holes 4 c.Additionally, by optimizing the flow velocity of the cooling air flowinginto the transition piece 1 and preventing it from entering thecombustion gas vigorously, the film-cooling effect is enhanced. Theangle α formed by the above-mentioned bottom surface of the transitionpiece 1 and the cooling holes 1 e and 1 f is approximately 30 degrees inthe embodiment of the present invention. This is determined by the rightbalance between angle-formation and film-cooling effect but the presentinvention is not limited to this angle.

FIG. 2 is a plane view showing the impingement-cooling plate inaccordance with the embodiment of the present invention. In theembodiment of the present invention, as shown in the figure, impingementholes 4 c are arranged in two rows in a zigzag pattern over the entirelength longitudinally on the top surface (a face corresponding to theabove-mentioned wider side) of the impingement-cooling plate 4. Thismakes it possible to achieve the impingement-cooling effect all over theentire length and entire width of the impingement-cooling plate 4.However, the arrangement of the impingement holes 4 c are not limited tothe construction in accordance with the embodiment of the presentinvention.

FIG. 3 through FIG. 5 show arrangements of cooling holes made in thetransition piece in accordance with the embodiment of the presentinvention. First, FIG. 3 is a cross-sectional view of the transitionpiece 1 viewed in the direction of combustion gas flow, includingcooling holes 1 e. FIG. 4 is a cross-sectional view of the transitionpiece 1 viewed in the direction of combustion gas flow, includingcooling holes 1 f. FIG. 5 shows the bottom surface of the transitionpiece 1. This figure mainly depicts the arrangement on the right side,viewed from the downstream side of combustion gas.

As shown in these figures, a plurality of cooling holes 1 e and 1 f arearranged symmetrically in one row each on the bottom surface of thetransition piece 1. The cooling holes 1 e on the upstream side of thecombustion gas are in a short row and are arranged in the centralportion only. Namely, cooling holes are arranged in two rows in thecentral portion at the outlet of the transition piece only, while theyare arranged in one row in the surrounding neighborhood, therebyachieving a construction to intensively cool the central portion, whichreaches high temperature. However, the central portion may beconstructed in such a manner as the cooling holes are arranged thereinin a plurality of rows, which is not limited to two rows but may be morethan two.

FIG. 6 is a transverse sectional view showing a construction of theneighborhood of an end portion of the impingement-cooling plate inaccordance with the embodiment of the present invention. FIG. 6A showsthe left side viewed from the downstream side of combustion gas and FIG.6B shows the right side, respectively. As shown in these figures, in theneighborhood of each end portion of the impingement-cooling plate 4 isinstalled a cover plate 7 whose cross section is approximately shaped ina letter of S. One end “e” on the upper side thereof is fixed to thetransition piece 1 by welding, while the other end “f” on the lower sidethereof is a free end, which comes into contact with the bottom surfaceof the impingement-cooling plate 4 by its own elastic force.

The above-mentioned state will make it possible to avoid thermal stressgenerated to the rib 1 d from affecting the impingement-cooling plate 4,for example, and to seal the above-mentioned gap formed between theimpingement-cooling plate 4 and the transition piece 1 on both right andleft sides thereof. By this sealing construction and by theabove-mentioned sealing construction on the side of the rib 1 d,compressed air from the compressor is introduced to the impingement hole4 c efficiently, thereby enhancing the impingement-cooling effect.

FIG. 7 shows the construction of transition piece seals in accordancewith the embodiment of the present invention. This figure shows thetransition piece seal viewed from the downstream side of the combustiongas. As shown in the figure, the right end of the transition piece seal2 on the left side as faced has a slot portion 2 c and a protrusionportion 2 d formed continuously thereon, and in order to engage intoeach portion respectively, a protrusion 2 d and a slot portion 2 c aremounted continuously on the left end of the transition piece seal on theright as faced. Then, the protrusions 2 d engage into confronting slotportions 2 c respectively so as to overlap each other.

A plurality of the transition piece seals 2 are provided not only to acombustor (which is not illustrated) but also to a transition piece, andare arranged all over the periphery of a gas turbine in successivecontact with each other. A gap between the transition piece seals 2 isequipped with an overlapping construction as shown in FIG. 7, whichmakes it possible to prevent compression air from the compressor fromleaking through the gap formed by the transition piece seals 2, therebyreducing worthless consumption of cooling air and enhancing the totalcooling effect at the outlet of the transition piece.

As a result of achieving the cooling construction as mentioned above,compared with a conventional structure, a temperature decrease such as56 to 102° C. in the central portion at the outlet of a transition pieceand 9 to 23° C. in the surrounding neighborhood, for example, could beobserved, and a favorable cooling effect was achieved.

While there have been described herein what are to be consideredpreferred embodiments of the present invention, other modifications andvariations of the invention are possible to be practiced, provided allsuch modifications fall within the spirit and scope of the invention.

With the present invention, it is possible to provide a coolingconstruction of a transition piece of a gas turbine which is simplyconstructed but can enhance the cooling effect at the outlet portion ofthe transition piece.

1. A cooling construction of a transition piece of a gas turbinecomprising: a first protrusion and a second protrusion that are mountedon said transition piece orthogonally to a main stream direction of saidtransition piece on a gas turbine inside diameter side of saidtransition piece and adjacent to an outlet portion of said transitionpiece; an impingement-cooling plate that is fixed at one end in acantilever state to said first protrusion, and is contacted at a tip ofthe other end of said impingement-cooling plate with said secondprotrusion so as to move back and forth along said second protrusion inresponse to thermal stress generated therearound; an elastic plate thatis fixed at one end to said second protrusion, and is contacted at theother end of said elastic plate with said other end of saidimpingement-cooling plate; and a pin that is provided on said transitionpiece for securing a predetermined gap between said transition piece andsaid impingement-cooling plate, wherein said elastic plate seals a gapbetween said transition piece and said impingement-cooling plate.
 2. Thecooling construction of a transition piece of a gas turbine according toclaim 1, further comprising: a face of said transition piece, thatconfronts said impingement-cooling plate; and a plurality of coolingholes that is provided only on a central portion of said transitionpiece in a row extending across said face perpendicular to the directionof combustion gas flow through said transition piece; wherein a centralportion only of said transition piece comprises a plurality of rows ofsaid cooling holes.
 3. The cooling construction of a transition piece ofa gas turbine according to claim 2 wherein said gas turbine is providedwith a plurality of said transition pieces, the cooling constructionfurther comprising transition piece seals that are provided at saidtransition pieces respectively, wherein end portions of said transitionpiece seals have protrusions mounted so as to overlap each other.
 4. Thecooling construction of a transition piece of a gas turbine according toclaim 1 wherein said gas turbine is provided with a plurality of saidtransition pieces, the cooling construction further comprisingtransition piece seals that are provided at said transition piecesrespectively, wherein end portions of said transition piece seals haveprotrusions mounted so as to overlap each other.
 5. The coolingconstruction of a transition piece of a gas turbine according to claim1, wherein said second protrusion is provided on a combustion gasupstream side of said first protrusion, and said second protrusion has ashape of a brim extending toward the gas turbine inside diameter side.6. The cooling construction of a transition piece of a gas turbineaccording to claim 1, wherein said impingement-cooling plate is biasedat said other end thereof in a direction orthogonal to the main streamdirection of said transition piece by an elastic force of said elasticplate so as to keep said other end contacted with said pin.